CNC Drilling Path Control With Curved Retraction Motion
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Solution Overview
Problem
Existing machine tool control methods face challenges in managing tool movement at discontinuous points, leading to potential interference with the workpiece due to suboptimal path planning, especially when vertical and horizontal movements are temporally overlapped.
Innovation Solution
A numerical value controller for machine tools that includes a storage unit, control unit, distance calculating unit, and curvature calculating unit to manage tool and workpiece movements along calculated curved paths, ensuring the tool is retracted reliably and preventing interference by dynamically adjusting the curvature based on retraction distances and drilling positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tool moves along a straight path with discontinuous points, then the programming is simple, but the tool pauses at each corner causing potential interference with the workpiece
Solution Approach 1:
The patent applies curvature by generating circular-arc-like curved paths instead of straight lines with corners. The control unit calculates curved movement paths that connect drilling positions smoothly, eliminating sharp corners where the tool would pause and potentially interfere with the workpiece.
Solution Approach 2:
The system dynamically adjusts the movement path based on real-time calculations. The curvature radius and path geometry are dynamically determined based on the drilling position, retraction distance, and tool characteristics, allowing the system to adapt to different machining scenarios while maintaining smooth continuous motion.
2Reliability
If vertical and horizontal movements are temporally overlapped to create curved paths, then continuous tool movement is achieved, but the path curvature must be precisely controlled to prevent workpiece interference
Solution Approach 1:
The control unit performs preliminary calculations of the curved path parameters before executing the drilling cycle. By pre-calculating the curvature radius and path geometry based on the retraction distance and drilling position, the system prepares the optimal movement trajectory in advance, ensuring smooth continuous motion without interference.
Solution Approach 2:
The system uses feedback from the calculated path parameters to adjust the temporal overlap between vertical and horizontal movements. The control unit continuously monitors the tool position and adjusts the movement timing to maintain the desired curvature, ensuring the tool follows the predetermined safe path.
3Reliability
If the tool retracts to a return point before the next drilling position, then interference is prevented, but the cycle time increases
Solution Approach 1:
The patent maintains continuity of useful action by overlapping the tool retraction to the return point with the horizontal movement to the next drilling position. Instead of completing retraction before starting the next move, the system initiates horizontal movement while the tool is still retracting, creating a smooth continuous trajectory that eliminates idle time and maintains high productivity.
Data Source
AI summary
A numerical value controller includes: a storage unit storing a machining program involving executing canned cycles including a first operation for moving a tool to a return point, a second operation for positioning a drilling position of a workpiece relative to the tool, a third operation for moving the tool from the return point to a hole bottom point, and a fourth operation for moving the tool from the hole bottom point to a terminal point located toward the hole bottom point relative to the return point; a control unit controls relative movement between the tool and the workpiece based on the machining program and moves the tool along curved paths by starting the second operation before the first operation ends and by starting the third operation before the second operation ends; and a distance calculating unit calculates a retraction distance from the workpiece to the return point.